It is known to produce certain N-substituted alkanediamines and various alkanolamines from dichloroalkanes and alkylene oxides, respectively. These starting materials are expensive and/or extremely toxic. The toxic nature of some of the alkylene oxides is a special problem for small-scale users, since the unit costs of installing safe-guards and monitoring systems increase with decreasing production scale.
Previous prior art attempts at aminating alkanediols have been limited to high temperature reactions utilizing heterogeneous catalysts. The high temperatures required in the prior art methods led to high operating pressures and low selectivities.
A limited number of prior art disclosures describe the use of homogeneous catalysts, e.g. RhH(PPh.sub.3).sub.4, for the reaction of monoalcohols with amines. (See, for example, Grigg, et al, J. C. S. Chem. Comm., pp 611-612 [1981]).
European Patent Publication No. 034,480 describes in general the preparation of N-alkylamine or N,N-dialkylamine by reacting a primary or secondary amine with a primary or secondary alcohol in the presence of certain noble mtal catalysts, such as the metal, salt or complex of the noble metal. The preferred example of catalyst is a rhodium hydride-triphenylphosphine complex. Although the disclosure is concerned largely with reactions involving monofunctional alcohols, there is also disclosed the reaction of a primary amine with a diol for the formation of heterocyclic ring compounds containing the amine N atom. For this purpose, the diol used should contain at least four atoms in the chain so that cyclization can occur. The publication contains no disclosure of reaction of a diol with secondary amine, wherein cyclization is not possible.
An article by Murahashi, et al. in Tetrahedron Letters (vol. 23, No. 2, pp. 229-232, [1982]) describes the synthesis of secondary amines by reaction of alcohols with amines in the presence of RuH.sub.2 (PPh.sub.3).sub.4 catalyst. By the reaction of butane diol or higher alkane diols with n-hexylamine, N-heterocyclic compounds are formed.
U.S. Pat. No. 3,708,539 discloses the condensation of amines with alcohols in the presence of ruthenium or certain other noble metal catalysts introduced as halides. The process is preferably conducted in the presence of a biphilic ligand of the structure ER.sub.3, wherein E may be phosphorus or arsenic. Particular examples are directed to (1) reaction of butanol with dibutylamine obtaining tributylamine; (2) using hexanol as reactant in the same manner resulted in the formation of dibutylhexylamine.
U.S. Pat. No. 4,487,967 discloses a process for selectively preparing severely sterically hindered secondary aminoether alcohols by reacting a primary amino compound with a polyalkenyl ether glycol in the presence of a hydrogenation catalyst at elevated temperatures and pressures.
Reaction of diols with ammonia or alkylamines to produce diaminoalkanes is disclosed in U.S. Pat. No. 3,270,059. The reaction is carried out in the presence of hydrogen at 150.degree.-300.degree. C. and at a pressure of at least 10 atmospheres, over a solid catalyst which contains at least one metal from the group consisting of cobalt and nickel. When secondary amines are employed as reactants, tertiary diamines are obtained. Reaction of ethylene glycol with diethylamine under the conditions of the patent yields chiefly tetraethylethylene diamine and a lesser amount of diethylethanolamine.
The selective conversion of primary amines to yield (I) N,N-dimethylalkyl- or (II) N,N-dialkylmethyl-amines by reaction with methanol in the presence of RuCl.sub.2 (Ph.sub.3 P).sub.3 catalyst, is disclosed in an article by Arcelli, et al. in the Journal of Organometallic Chemistry (vol. 235, pp. 93-96 [1982]). The selectivity towards the I or II type compound is controlled by choice of the amount of catalyst and the ratio of reactants.